STAPLE / FILAMENT YARN SPINNING SYSTEMS

STAPLE YARNS:

Yarns can be made of staple fibres by any one of severaltechniques

The method used is depended upon factors such as:

1. Manufacturers preference of equipment2. Economic implications3. Fibres to be used4. Desired properties of the yarn

The value and character of yarn are determined by

1. Kind and quality of fibre2. Amount of processing necessary to produce fineness3. Amount of twist which increases strength in the final yarn

Staple spinning Processes:1. Conventional ring spinning2. Open end spinning or rotor spinning3. Friction spinning4. Self twist spinning5. Electrostatic spinning6. Vortex spinning7. Air-jet spinning8. Twist less spinning (Twilo)

1. Conventional ring spinning:

The roved sliver passes through several sets of rollersrunning at successively higher rates of speed and is finallydrawn out to yarn of the size desired

Ring spinning is more suitable for the cotton yarn mass production. The highest rpm and constant spinning action provides fast operation.

It completes yarn formation through 3 steps.Drawing out the rovingInserting twistWinding the yarn on bobbins

2. Open end spinning (O-E) or rotor or break spinning

A relatively recent devpt. in the production of spun yarn

This technique is widely accepted as a satisfactory process for spinning coarser yarns of counts of upto about 40

The open end spinning begins with the carded sliver, whichPasses through a set of rollers revolving at progressive speedsthere by completely opening the sliver.

The fibres are fed individually by a stream of air in to the inner groove of funnel shaped rotor rotating at a very high speed.

The centrifugal force of the rotor builds up a multi layer of fibres which is peeled away from the collecting groove as it is simultaneously twisted by the rotation of the rotor and withdrawn continuously, thus being formed in to a yarn.

RING SPINNING OPEN END SPINNING

Bobbin rotates constantly for Spool does not need to beinsertion of twist rotated to insert twist

Cannot handle spools of Much larger spools bigger size can be wound

Can spin finer yarns Can spin coarser/ carded yarns

Faster production 3-5 times faster than ring spinning

Uniform and strong yarn Uniform but flexible yarn with better dye ability

RING SPINNING OPEN END SPINNING

Combed yarns (finer) Carded yarns (coarser)

Yarns for varied Yarns for heavier fabrics applications such as denims, towels and

poplins

Stronger 20% more twisted but 15-20% weaker as the yarn is coarser

Suitable for all staple Not suitable for man-madefibres staple fibre spinning except rayon

as the fibre finish clogs the rotor

3. Friction spinning

Commercialized under the trade mark DREF

It is a variation of the Open end spinning system

The principle of the technique is that passing along the longitudinal drum axis a stream of carded fibres in the roll nip of perforated drums, both of which are rotated in the same direction.

This action forces the fibres to be wedged along the nip there by becoming compressed; The friction of the rollers cause the fibres to twist around each other

4. Self twist spinning:

A process developed for wool and wool like fibres

Pairs of rovings are drawn out on a succession ofdrafting rollers, the last set of which moves sideways causing a rolling action of the strands to wraparoundeach other

Some times additives are used for the cohesionThe self twist process can spin worsted yarn of good qualityupto 10 times faster than conventional spinning

5. Electrostatic spinning

The technique utilises a non uniform electrostatic fieldwhich can efficiently separate short staple fibres fromthe long staples to produce a yarn of more strength and uniformity

Twilo: A twist less spinning process, which forms a yarnby temporarily binding the fibres together with an adhesive(water soluble agent) and subsequently removing the adhesive after the yarn has been made in to a fabric

Filament yarn spinning systems:

1. Wet spinning2. Dry spinning3. Melt spinning4. Bicomponent spinning5. Biconstituent spinning6. Film splitting7. Integrated multicomponent yarns8. Coverspun yarns9. Selfil tyarns10. Aerodynamic spinning

Bi component spinning:

The technique involves extrusion through a spinneretof two different types of the same polymer

There are three methods of bicomponent yarn production1. Side by side extrusion2. Extrusion through one spinneret enclosed in an other3. Distribution of drops of molten polymers

Bicomponent fiber /yarn

Biconstituent spinning:

This technique utilizes two different polymers thatare combined and extruded in the same manner

Film Splitting:

Melt extrusion of polymer through a wide die but witha very narrow slit to form a sheet of film which is later broken /cracked by mechanical means in to a mat of fibresOr embossed with a roller having patterned indentations to fibrillate the film

Integrated multi component yarns:

1. Integrated composite spinning(ICS)The process entails passing a monofilament or a multifilament strand (Carrier) through a poly propylenePolymer (binder resin) and then immediately embedding part of the length of staple fibres in to the polymeric resin

Different types of staples of different sizes and colourscan be used to incorporate desirable properties, effects andappearances.

2. Cover spun:

The technique wraps fine continuous filament man made fibrearound a core of untwisted natural or man made staple fibre to produce yarns in a wide range of counts.

Selfil: The self twisted staple core is initially wrapped with a filament yarn in alternating S and Z phases; a second filament yarn is then wrapped around these in alternating opposite Z and S twists.

Aerodynamic Spinning: This system passes a continuousMulti filament yarn together with staple fibre through aPneumatic device which causes the filaments to twist and curlentrapping the staple fibres in the snarls.

Types and characteristics of yarns:

1. Single yarns2. Ply or folded yarns3. Doubled yarns or compound yarns4. Cabled yarns or cords5. Textured yarns: Stretch yarns, Bulk yarns6. Novelty yarns:

• Slub yarns• Flake yarns• Spiral yarns• Ratine yarns• Boucle, Loop or Curl yarns• Nub, Knop, Knot or Spot yarns• Chinelle yarns

VarietiesBoucleLoopGimpNepChenille CorkscrewCore spunMetallic

Novelty yarns / Fancy yarns / Complex Yarns

ASTM defines fancy yarn as:

A yarn that differs significantly from the normal appearance of single or plied yarn due to the presence of irregularities deliberately produced during its formation.

In single yarns the irregularities may be due to the inclusion ofknots, loops, curls, slubs and the like.

In plied yarns, the irregularities may be due to a variabledelivery of one or more of its components or twisting togetherdissimilar single yarns.

Slub yarns:

Slub yarns have soft untwisted areas at frequent intervalsthroughout their length.

They are coarse with slight twist, having varying ddiameters that show irregularities typical of anincomplete spinning operation

Features: simulates linen yarnnot durableused in shantung and tweeds

Flake yarns:

Variation of slub yarn

The flake or slub effect is made by insertingsoft, thick tufts of roving between binder yarns atintervals.

Spiral yarns or Cork Screw yarns:

The general appearance of spiral yarn is that of a coarse yarnwound around a fine yarn giving the effect of a spiral. The thicker yarn is given a slack twist and wound spirally around a finer yarn which is given a hard twist.

Ratine yarns:

A variation of spiral yarn : The outer yarn (effect) and the core yarn are twisted in a spiral manner, butat intervals a longer loop is thrown out by the effect yarnwhich kinks back on itself and is held in place by a third (binder) yarn.

Boucle, Loop or Curl yarns:

These yarns are comparable to the ratine yarns but in this type, the yarns are more softer with more pronounced novelty effect or loops

Nub, Knop, Knot or Spot yarns:

The effect ply is twisted around the core ply many times within a very short space, causing bumps or nubsthat may be spaced at intervals along the yarn.

‘Chenille’ yarns: the name derived from French Caterpillar

It is a yarn with a velvet like or pile surface. The effect is achieved by a core of two yarns plied together and firmly holding short tufts of soft-twisted yarns between the twists along the core’s length.

A leno weave fabric with soft filling yarns held within the twists of the warp is split in to strips between the warps